In general, an engine of internal combustion type is commonly used in a vehicle as a power source for running. In recent years, a continuously variable transmission has increasingly been used as a transmission for transmitting power generated by an engine to the driving wheels. Such an engine and continuously variable transmission are controlled by a power control device, which controls them when the vehicle is running. Such a power control device exerts operating control for an engine and transmission control for a continuously variable transmission according to driving operations performed by a driver and the current running state of the vehicle.
For example, in the control apparatus for a vehicle that includes a continuously variable transmission, described in the Patent Literature 1, a target driving force is calculated from the degree of opening of an accelerator or vehicle speed, and a target output is based on this driving force. Thus, the final target operating point, which is a combination of the target revolution speed and target torque of the engine is calculated. This final target operating point is an operating point determined taking fuel consumption into account among operating points capable of actualizing the target driving force. Moreover, a transition operating point, which is a combination of the revolution speed and torque of the engine attainable within a predetermined period from the present, is calculated based on, for example, the degree that supercharged pressure applied by a supercharger provided for the engine increases.
Moreover, when the transition operating point thus calculated has reached an operating point that is located on the output contour line passing through the final target operating point but that has not reached this final target operating point, the torque and revolution speed of the engine are shifted so that the operating point reaches the final target operating point along the output contour line. That is, the operating point is shifted by controlling the engine torque and controlling the transmission ratio of a continuously variable transmission so that the operating point on the output contour line reaches the final target operating point. Thus, revolution speed and torque of the engine can be increased to the maximum within the attainable range, and the operating point can reliably be caused to reach the final target operating point, thus reducing delay in acceleration of the vehicle.
Patent Literature 1: Japanese Patent Application Laid-open No. 2003-39990